Cutters are employed for pulling down a concrete building and for cutting an opening in a floor or a wall surface for reforming a building; and most of them are hand held cutters. However, there is a problem in that a cutting operation with a hand held cutter is heavy labor, so that the efficiency of the operation is low, and also it is hard to cut a high portion.
Then, in order to improve the efficiency of the operation, there has been suggested a structure in which a self-propelled chain cutting device is mounted to a rail and the rail is anchored to a material to be cut so as to self-propel the chain-cutter along the rail, thereby cutting the material to be cut. The rail can be mounted to a small back hoe machine. However, there is a problem in that the operation is limited since the machine can cut only in a direction perpendicular to the back hoe machine.
In order to solve the problem mentioned above, there is suggested in Japanese Patent Publication No. 7-13376 a supporting apparatus for a wall surface excavating chain cutter, which mounts the chain cutting device to a distal end of an operating machine arm of a traveling truck in a freely swinging manner.
FIG. 30 is a side elevational view of the supporting apparatus for the wall excavating chain cutter, in which a guide rail 91 is mounted to the distal end of a operating machine arm 90 of a hydraulic excavator in such a manner as to freely swing in a horizontal direction, thereby being swingable by a hydraulic cylinder 92 for swinging. Supporting leg frames 93 and 93 are provided at a lower side of both ends of the guide rail 91, and supporting leg shoes 94 and 94 are provided on a distal end of each of the supporting leg frames 93 and 93 in such a manner as to freely adjust the height thereof. A chain cutter 95, structured such as to be freely tilted upwardly and downwardly by a tilting hydraulic cylinder 96, is mounted to the guide rail 91. The chain cutter 95 is structured such as to be capable of being moved in a horizontal direction along the guide rail 91 by a hydraulic cylinder 97 for horizontal traveling.
When cutting a floor surface, as shown in FIG. 30, the supporting leg shoes 94 and 94 are brought into contact with the floor surface. Next, the chain cutter 95 is tilted downwardly from a position X, shown by a narrow two dot chain line, to a position, shown by a solid line, by the tilting hydraulic cylinder 96 so as to cut the floor to a depth of H. Next, the chain cutter 95 is horizontally moved along the guide rail 91 by the horizontal movement hydraulic cylinder 97 so as to excavate, as shown by a narrow two dot chain line Y.
Since the supporting apparatus is mounted to the distal end of the working machine arm 90 of the hydraulic excavator, it is possible to excavate not only the floor but also a wall; further, it is possible to excavate in an optional direction with respect to the hydraulic excavator, and it is possible to excavate a high portion.
However, the conventional structure mentioned above has the following problems.
(1) Since the chain cutter 95 is swung downwardly at a time of starting an excavation so as to deepen the cut depth, there is generated an incomplete cut portion for a length B2 before reaching the excavation depth H. Further, there is left an incomplete cut portion for a length D at a time of completing the excavation. Accordingly, as shown in FIG. 31, for example, when cutting a regular rectangular portion (a hatched portion) having a depth H and a length A along a line, the cut length C2 along the line is obtained by the following formula. EQU C2=A+B2+D PA1 Therefore, there is a lot of wasteful cutting (=B2+D), and a wide cut area is required. PA1 (2) Since the guide rail 91 is fixed to the floor surface by the, supporting leg frames 93 and 93, the center portion thereof is floated. Accordingly, when cutting a Hume pipe or the like, it is impossible to hold the Hume pipe or the like, and it is required to independently fix the Hume pipe or the like, so that the operation is troublesome. PA1 (3) Since it is necessary to periodically adjust a tension when the chain of the chain cutter 95 is abraded, it is troublesome. Further, since it is impossible to always maintain a proper tensile state, a cutting efficiency is deteriorated, and an abnormal abrasion is generated in the chain, a sprocket for driving the chain, a chain bar or the like, so that a deterioration of the service life thereof is caused. PA1 (4) Since the distal end of the chain cutter 95 is vibrated due to a reaction force at a time of cutting, it is impossible to accurately and neatly cut. Further, since an abrasion and a crack of the chain bar are easily generated, and an abrasion of the chain and the driving sprocket is hard, the frequency of replacing parts is increased and a deterioration of a cutting capacity is caused. PA1 a guide supporting member, which is mountable to a distal end of a working machine on a self-propelled working vehicle in such a manner as to freely swing; PA1 guiding means, horizontally supported by the guide supporting member; PA1 a cutter, mounted to the guiding means; PA1 vertical movement means for moving the cutter in a direction perpendicular to the guiding means; and PA1 horizontal movement means for moving the cutter in a horizontal direction along the guide means.
In this case, when the load becomes high during a cutting by the chain cutter 95, there is a case that a speed of rotation of the chain cutter 95 is lowered and the chain cutter 95 sometimes stops. On the contrary, when the load becomes low, a power loss is generated unless a feeding speed of the chain cutter 95 is increased. Accordingly, it is necessary to adjust them during the operation. These adjustments have been conventionally performed in accordance with an operator determining a load state while monitoring, for example, an oil pressure gauge, and manually controlling the rotational speed and the feeding speed of the chain cutter 95. Therefore, there has been a problem in that it requires a lot of skill to operate the apparatus, and it is hard to effectively perform a cutting operation.